National has announced that it will set up a $100 million fund to buy and retire farmland next to important waterways. The idea is that it will create an environmental buffer to improve water quality. Further, by July 2017 it will be illegal not to have waterways fenced off.

On the face of it, it’s a good policy. Why wouldn’t you want to improve water quality by setting up buffer zones to keep cattle out? What could be wrong with fencing off paddocks from the river?

Well, even Amy Adams, National’s Environment Minister admits that 90% of waterways next to farms are already fenced off, and as Andrew Hoggard, the Federated Farmers dairy chairman, says, a ban was effectively already in place:

“It’s in our conditions to supply to Fonterra. If you don’t meet the conditions of supply, they won’t pick your milk up, and you’ll be out of business…